Breathing assistance apparatus

ABSTRACT

A pressure regulating device includes a housing having a gases inlet adapted to in use be in fluid communication or integrated with a breathing assistance apparatus which conveys gases to an infant or a neonate requiring breathing assistance, an outlet adapted to be in use in fluid communication with said infant, and an aperture which enables the venting of a portion of gases that in use are passing through the housing from the inlet to the outlet. A tube inlet on the housing is adapted to receive a surfactant delivery device therethrough to enable administration of surfactant to the infant or neonate. A sealing mechanism seals around the surfactant delivery device and is adapted to normally fluidically seal the tube inlet and in use allow the surfactant delivery device to pass through the tube inlet.

This application is a division of U.S. patent application Ser. No.10/357,753, entitled “Breathing Assistance Apparatus” which has a filingdate of Feb. 4, 2003 which claims priority of New Zealand Patent Nos.517030, filed on Feb. 4, 2002 and 518289 filed on Apr. 10, 2002, all ofwhich are hereby incorporated by reference in their entirety.

FIELD OF THE INVENTION

The present invention relates to the use of a pressure regulator inconjunction with a breathing assistance apparatus, particularly thoughnot solely, for regulating the pressure of gases supplied to a patientfrom a Positive End Expiratory Pressure (PEEP) apparatus or for aninfant resuscitation device.

BACKGROUND

At the moment of their first breath, a baby's lungs are collapsed andfilled with fluid. The pressures needed to open such lungs, and keepthem open, are several times that of a normal breath until the fluid isdisplaced and the lungs have filled with air. To generate these largepressures, the baby must have strong respiratory muscles, as well as achemical called surfactant in their alveoli. Surfactant reduces thesurface tension of the fluid within the alveoli, preventing the alveolarwalls from sticking to each other, like coasters to coffee cups whenthere is water between them.

Neonates have difficulty in opening their lungs and keeping them open.Reasons for this include:

a) Weak respiratory muscles and low surfactant levels. This means thatthey cannot generate enough pressure to open the lungs and, should theybe resuscitated, tire quickly with the effort of keeping open alveolilacking in surfactant.

b) Underdeveloped internal tissue structure to support the alveoli.

c) Slower clearance of lung fluid. In very premature neonates, fluid maycontinue to be secreted in the alveoli even after birth.

d) A soft chest wall, horizontal ribs, and a flatter diaphragmcontribute to reduce the inspiratory capacity.

e) The mixing of oxygenated and deoxygenated blood raises blood pressurein the lungs, increasing fluid movement from the blood vessels into thelung tissue. The reduced blood oxygen level starves tissue of oxygen andfarther weakens respiratory muscles.

f) Weak neck muscles and a lack of neck fat reduce upper airwaystability so that collapse on inspiration may occur.

g) Collapsed, damaged alveoli secrete proteins that reduce surfactantfunction.

To alleviate this it is known to apply Positive End Expiratory Pressure(PEEP) during respiration, resuscitation or assisted respiration(ventilation). In applying PEEP, the neonate's upper airway and lungsare held open during expiration against a pressure that stops alveolarcollapse. Lung fluid is pushed back into the circulating blood, alveolarsurfactant is conserved, and a larger area of the lung participates ingas exchange with the blood. As blood oxygenation and carbon dioxideremoval improves, more oxygen is delivered to growing tissues, whileless oxygen and energy is consumed by respiratory muscles. In the easeof resuscitation or ventilation the pressure is varied between a PeakInspiratory Pressure (PIP) and the PEEP value until the patient/infantis breathing spontaneously.

In order to provide the PEEP across a range of flow rates, some methodis required to regulate the pressure. It is known in the art to providea valve near the infant, which actuates at a level of pressure (i.e.:the PEEP value) to allow the gases to vent externally. Such valves mayemploy a spring-loaded valve, which in turn requires the use of highquality springs, which have been individually tested to give a hightolerance spring constant in order to ensure that it actuates at a valuesubstantially that of the maximum safe pressure. Both the manufactureand testing of such a spring necessitates that its cost will becorrespondingly high. Accordingly it would be advantageous to provide apressure relief valve for a breathing assistance system which did notinvolve the use of such a high tolerance spring.

Also such valves are known to have substantial variation of the reliefpressure with flow rate. For example as seen in FIG. 5 the deliveredpressure is shown for a range of valves. Over a given range of flowrates 50 a variable orifice 52 gives a wide range of delivered pressure.An improvement on this is a prior art umbrella valve (for example the“umbrella check valve” manufactured by Vernay Laboratories Inc. shown inFIGS. 4a and 4b ) which delivers a lower variation 54 in deliveredpressure. However in all cases the variation in delivered pressure ofprior art valves would desirably be reduced for this application.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a pressure regulatorwhich goes some way to achieving the above-mentioned desiderata or whichwill at least provide the Healthcare industry with a useful choice.

The pressure regulating device is used with a breathing assistanceapparatus which conveys gases to an infant or a neonate requiringbreathing assistance. The pressure regulating device includes a housingincluding a gases inlet adapted to in use be in fluid communication orintegrated with a breathing assistance apparatus, an outlet adapted tobe in use in fluid communication with said infant, and an aperture whichenables the venting of a portion of gases that in use are passingthrough the housing from the inlet to the outlet. The housing alsoincludes a tube inlet adapted to receive a surfactant delivery devicetherethrough to enable administration of surfactant to the neonate. Asealing mechanism seals around the surfactant delivery device and isadapted to normally fluidically seal the tube inlet and in use allow thesurfactant delivery device to pass through the tube inlet.

To those skilled in the art to which the invention relates, many changesin construction and widely differing embodiments and applications of theinvention will suggest themselves without departing from the scope ofthe invention as defined in the appended claims. The disclosures and thedescriptions herein are purely illustrative and are not intended to bein any sense limiting.

The invention consists in the foregoing and also envisages constructionsof which the following gives examples.

BRIEF DESCRIPTION OF THE DRAWINGS

One preferred form of the present invention will now be described withreference to the accompanying drawings in which:

FIG. 1 is a block diagram showing a typical configuration for supplyingbreathing assistance to a neonate in accordance with the prior art,

FIG. 2a is a sectional view of a typical layout of a pressure regulatorthat can be used with the apparatus of FIG. 1, according to thepreferred embodiment of the present invention.

FIG. 2b is a perspective view of the valve member used with the pressureregulator of FIG. 2a , according to the preferred embodiment of thepresent invention.

FIG. 3 is a side view showing hidden detail of the valve member of FIG.2b , according to the preferred embodiment of the present invention.

FIG. 4a is a side view showing hidden detail of a prior art umbrellavalve.

FIG. 4b is a perspective view of a prior art umbrella valve of FIG. 4 a.

FIG. 5 is a graph showing comparison of the pressure ranges produced bydifferent types of valve over a flow range of 5-15 liters/minute.

FIG. 6 is a sectional front elevation view of a pressure regulatoraccording to a further embodiment of the present invention.

FIG. 7 is an exploded perspective view of the pressure regulator of FIG.6.

FIG. 8 is a front elevation of a pressure regulator according to a stillfurther embodiment of the present invention.

FIG. 9 is an exploded perspective view of the pressure regulator of FIG.8.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention includes a connector including a valve, for usewhen resuscitating an infant or neonate. The delivered pressure isvaried between Peak Inspiratory Pressure (PIP) and Peak End ExpiratoryPressure (PEEP) by the occlusion of a PEEP outlet on the valve. The PEEPoutlet may either allow variable PEEP, by adjustment, or substantiallyflow independent fixed PEEP using a novel umbrella valve. In thepreferred embodiment, a duck billed valve is included for suctioning ofsurfactant delivery during resuscitation. In the preferred embodiment,the connector is adapted to one handed use. If using the fixed PEEPvalve, this avoids the need for adjustment as flow through the valvechanges, and provides more effective therapy.

Referring now to FIG. 1 a typical application as known in the prior artis depicted. A Positive End Expiratory Pressure (PEEP) system is shownin which an infant 119 is receiving pressurized gases through a nasalmask 128 (or endotracheal tube or other interface as are shown in theart) connected to an inhalatory conduit 121, preferably forresuscitation. Either the mask 128 or the inhalatory conduit 121 caninclude the pressure regulator 134 of the present invention, to controlthe pressure of gas delivered to the infant. The inhalatory conduit 121is connected to the outlet of a resuscitator apparatus 115, which is inturn connected to a flow regulator and air supply 118 (which providesgas to the resuscitator at 50 psi or thereabouts).

It should be understood that the present invention, however, is notlimited to resuscitation, or the delivery of PEEP gases but is alsoapplicable to other types of gas delivery systems.

The preferred embodiment of the pressure regulator 134 of the presentinvention is shown in FIGS. 2 and 3 in detail. In the preferredembodiment the regulator 134 is disposed within the mask 128 although itwill be appreciated that it can be located in a separate assembly, solong as it is proximate the infant.

Referring particularly to FIG. 2a we see a cross-sectional schematic ofthe preferred embodiment of the pressure regulator 134. The pressureregulator 134 includes a housing or manifold 300 with a gases inlet 302and two outlets 304, 306. The first outlet 304 supplies respiratorygases to the infant. The second outlet 306 is an external orifice which,as described previously, can be used to vary pressure between the PIPand PEEP. A gas passageway is defined between the gases inlet 302 andthe first outlet 304. In the illustrated embodiment, located between thegases inlet 302 and the orifice 306 is an improved PEEP valve 308.

The PIP is adjusted at the resuscitator 115 to a desired level. Thedelivered gases delivered to the infant 119 are varied between the PIP(with orifice 306 near the infant occluded), and the PEEP (with theorifice 306 un-occluded, so that a portion of the gas from toresuscitator 115 flows through the orifice 306). It can be seen thatresuscitation of an infant can be attempted by varying the pressure atoutlet 304 between the PIP and PEEP at a normal respiratory frequency.

The purpose of the PEEP valve 308 is to keep the Positive End ExpiratoryPressure (PEEP) at a reasonably constant level, independent of changesin the overall flow rate of gases from resuscitator 115.

It is desirable for infant respiratory assistance that the PEEP valueshould be approximately 5 cmH₂O, independent of the flow rate.Preferably the interfaces of the type used for resuscitation need to besimple and cost effective, as these are single-use products. Also, dueto the nature of this application, a valve with many small separateparts, such as a spring valve, is not a viable option.

The preferred embodiment, the PEEP valve 308 is a small umbrella valve308, made of an elastomeric material, and positioned on a valve seat 310as shown particularly in FIGS. 2a & 2 b. Valve seat 310 defines aninternal venting aperture 311 which is covered and closed by the valve308 in a closed position. Preferably the valve 308 and seat 310 areincluded as part of the nasal mask 128, or as part of an endotrachealtube (not shown). As the overall flow rate is increased, the consequentincrease in pressure inside the manifold 300 causes the umbrella valveflaps 312 to lift up from the valve seat 310, thereby letting more airout from inside the manifold 300, and therefore keeping the pressureinside the manifold 300 at a constant level.

The umbrella valve 308 of the present invention differs from other priorart umbrella valves in the material and dimensions, the material beingSilastic liquid silicone rubber Q7-4840. The overall proportions of theumbrella valve are as shown in FIG. 3. In particular, comparing FIG. 3to the prior art valve shown in FIGS. 4A and 4B, we see the presentinvention has a characteristic flap 312 which is thicker at theperiphery than at the centre. The ratio of the centre thickness to theperiphery thickness should be 2:3, giving the cross-sectional shapeshown in FIG. 3. The valve 308 of the present invention includes a shaft301, which has a retaining flange 303.

Due to the design used, the umbrella valve 308 of the present inventiondoes not act as a ‘pop-off’ valve. Most umbrella valves such as thatshown in FIGS. 4A and 4B are designed to open at a specific ‘crackingpressure’. The prior art valve shown in FIGS. 4A and 4B has a shall 400and flap 410. Often prior art valves have a “cracking pressure whichwill increase as the flow threshold increases”. In contrast, the valveof the present invention is designed to open at a predetermined flowrate (in this specific application below 5 liters/minute) and willcontinue to open further as the flow rate increases, increasing the flowthrough the internal aperture 311, and thus causing the pressure in themanifold 300 to remain constant as the flow from resuscitator 115increases. Prior art umbrella valves will open at a certain pressurelevel, and either will not open any further as the flow rate increases,or their resistance to opening will increase, so that there issubstantial variation of the relief pressure with flow rate. Thisvariation causes the pressure in a manifold to increase as the flow froma resuscitator increases.

The improved characteristics of the present invention can be seen inFIG. 5. If using a simple variable orifice valve, if the flow rate ischanged between 5 and 15 liters per minute a dramatic change in PEEPwill also occur, as shown by line 52. The PEEP range for the variableorifice valve is 13 cmH₂O. In tests, the best result obtained from priorart umbrella valves, as shown by line 54, was a PEEP range of 4.9 cmH₂O.In the same tests, the best result gained from the valve of the presentinvention as shown by line 56 is a PEEP range of 2.8 cmH₂O.

Referring to FIG. 6 we see an alternate embodiment of the pressureregulator 134. Located between the gases inlet 302 and the orifice 306is a PEEP valve 308, preferably the umbrella valve described previouslyfor the preferred embodiment. Included in this alternate embodiment is atube inlet 303 which includes a duck billed valve 305, used forintroducing tubes down the trachea of the infant 119, for suctioning,delivery of surfactant etc. the duck-billed valve 305 is normallyclosed.

In this alternate embodiment, the manifold 300 is shaped to enable easeof use; and it is designed to enable one handed operation. The manifold300 is preferably wide and short and in this embodiment, shown in FIG.6, it has generally cylindrical cross-section. At the outlet 304 to theneonate, which is connected to the manifold 300, is a flange 301. Whenthe present invention is used with a mask, the flange 301 enables theoperator to apply pressure, pushing the mask into position to seal themask around the neonate's nose and mouth. The flange 301 also enables anoperator to use one digit on their hand to occlude orifice 306, in orderthat they can vary pressure in the manifold 300 between PIP and PEEP.The operator achieves this variation in the pressure most easily byplacing their thumb and middle finger on the flange 301 at 309 and 360and then using their index finger to seal orifice 306. The orificebranch 321 is shown at an angle 309 to the manifold 300. This angle 309allows the index finger to be placed in a natural position to occludeorifice 306. The previously described embodiment of the pressureregulator 134 operates in the same way as the embodiment describedabove.

As has already been described, new born neonates often lack surfactantin their lungs. When the present invention is used with an endotrachealtube, surfactant can be administered to a patient without the need toremove the breathing assistance apparatus from the patient. By using awithout the need to remove the breathing assistance apparatus from thepatient. By pushing the end of the syringe through the duck billed valve305, located opposite the flange 301 at the outlet 304, and administerthe surfactant to the infant 119.

The duck billed valve 305 is normally sealed against the passage offluids, but upon insertion of a syringe, the duck-billed valve 305 opensto allow the syringe end to enter the interior of the manifold 307. Thebill, or inner end 320, of the duck billed valve 305 seals around theend of an inserted syringe, ensuring that the manifold 300 remainssealed. The valve bill 320 is manufactured from a silicone rubber, orother suitable material as known in the art. It is known that surfactantis a viscous fluid, and therefore this method of administration isadvantageous over the method of administering surfactant using multilumen endotracheal tubes.

The duck billed valve 305 can also be used to suction a neonate orinfant 119, to remove airway secretions. Suctioning is performed using acatheter inserted through the duck billed valve 305, inserting thecatheter through the duck-billed valve 305, then down the endotrachealtube. The bill 320 of the valve 305 seals around an inserted catheter sothat airway pressure is maintained. The duck billed valve 305 isretained in the manifold 300 in such a way that any instrument insertedin to the valve 305 is guided directly into the top of an endotrachealtube (or alternatively, a nasal mask, or other interfaces as are know inthe art), one end of the endotracheal tube fitted at the outlet 304.

FIG. 8 and FIG. 9 illustrate an alternate embodiment of the pressureregulator 134. The overall shape of the manifold 330 is similar to thatpreviously described with reference to FIG. 6, with, in this embodiment,orifice branch 321 replaced by an alternate orifice branch 326. Thepressure of the delivered gases is varied between PIP, with orifice 334on branch 326 occluded, and PEEP, with the orifice 334 un-occluded. Asis best shown with reference to FIG. 9, the manifold 330 includes a jetoutlet 332 positioned between the gases inlet 328 and the outlet orifice334. The flow rate of the gases through the jet outlet 332 is controlledby a screw-on cap 324, which is located screwed onto a thread of the endof the outlet branch 326 of the manifold 330. The traveled distance ofthe screw on cap on the thread determines the restriction to the orifice332 and therefore varies the PEEP. That is, the closer the screw on cap324 is to the jet outlet 332, the smaller the gas flow rate through theorifice 334. The manifold 330 otherwise described for thy, previousembodiments.

The invention claimed is:
 1. A pressure regulating device for use with abreathing assistance apparatus that conveys gases to an infant or aneonate requiring breathing assistance, the pressure regulating devicecomprising: a housing comprising: a gases inlet adapted to in use be influid communication or integrated with the breathing assistanceapparatus; a gases outlet adapted to in use be in fluid communicationwith the infant or the neonate, a gas passageway defined between saidgases inlet and said gases outlet; an external aperture that is separateand distinct from said gases inlet and said gases outlet, said externalaperture being fluidly connected to said gas passageway through a valve,said external aperture providing a vent to atmosphere, said valveconfigured to establish a peak expiratory end pressure at said gasesoutlet of said pressure regulating device, said external apertureconfigured to be occluded and un-occluded by a user to vary a pressureat said gases outlet between a peak inspiratory pressure (PIP) with saidexternal aperture occluded and a peak end expiratory pressure (PEEP)with said external aperture un-occluded such that a portion of saidgases flows through said external aperture to vent externally; and atube inlet adapted to receive a surfactant delivery device therethroughto enable administration of surfactant to the infant or the neonate,wherein said tube inlet opposes said gases outlet, and a sealingmechanism adapted to normally fluidically seal said tube inlet and inuse allow said surfactant delivery device to pass through said tubeinlet, said sealing mechanism sealing around said surfactant deliverydevice.
 2. A pressure regulating device as claimed in claim 1 whereinsaid gases inlet is located substantially on an opposite side of saidhousing from said external aperture.
 3. A pressure regulating device asclaimed in claim 2 wherein said housing also includes an orifice branchextending from a side of said housing, said orifice branch extending atan angle with respect to a central axis of said housing, said externalaperture located in said orifice branch.
 4. A pressure regulating deviceas claimed in claim 3 wherein said housing is substantially cylindrical.5. A pressure regulating device as claimed in claim 4 wherein said gasesinlet is arranged at an angle with respect to said housing.
 6. Apressure regulating device as claimed in claim 1 wherein said sealingmechanism is a duck billed valve.
 7. A pressure regulating device asclaimed in claim 6 wherein said valve comprises an umbrella valveconfigured to cover and close a passageway leading to said externalaperture in a closed position in addition to said duck billed valve. 8.A pressure regulating device as claimed in claim 7 wherein said umbrellavalve includes a continuous flap that is thicker at its periphery thanat its center.
 9. A pressure regulating device as claimed in claim 6wherein said tube inlet and said gases outlet are substantially coaxial.10. A pressure regulating device as claimed in claim 1 wherein saidhousing also includes an orifice branch extending from a side of saidhousing, said orifice branch extending at an angle with respect to saidhousing, said external aperture located in said orifice branch.
 11. Apressure regulating device as claimed in claim 10 wherein said housingis substantially cylindrical.
 12. A pressure regulating device asclaimed in claim 11 wherein said gases inlet is arranged at an anglewith respect to said housing.
 13. A pressure regulating device asclaimed in claim 1 wherein said valve comprises an umbrella valveconfigured to cover and close a passageway leading to said externalaperture in a closed position.
 14. A pressure regulating device asclaimed in claim 13 wherein said umbrella valve includes a continuousflap that is thicker at its periphery than at its center.
 15. A pressureregulating device as claimed in claim 1 wherein said housing comprises aflange at said gases outlet.
 16. A pressure regulating device as claimedin claim 1 wherein said tube inlet is configured to provide for theintroduction of tubes down into a trachea of the infant or the neonatein contact with said gases outlet.
 17. A pressure regulating device asclaimed in claim 1 wherein said tube inlet is configured to provide forthe administration of surfactant by pushing a syringe through said tubeinlet toward the infant or the neonate in contact with said gasesoutlet.
 18. A pressure regulating device for use with a breathingassistance apparatus that conveys gases to an infant or a neonaterequiring breathing assistance, the pressure regulating devicecomprising: a housing comprising: a gases inlet adapted to in use be influid communication or integrated with the breathing assistanceapparatus; a gases outlet adapted to in use be in fluid communicationwith the infant or the neonate, a gas passageway defined between saidgases inlet and said gases outlet; an orifice branch extending from aside of said housing, said orifice branch including a screw thread; ascrew-on cap configured to be screwed onto said screw thread of saidorifice branch, said screw-on cap including an external aperture that isseparate and distinct from said gases inlet and said gases outlet, saidexternal aperture providing a vent to atmosphere; a jet outletpositioned in said orifice branch between said gases inlet and saidexternal aperture, said external aperture being fluidly connected tosaid gas passageway through said jet outlet; and a tube inlet adapted toreceive a surfactant delivery device therethrough to enableadministration of surfactant to the infant or the neonate, wherein saidtube inlet opposes said gases outlet, and a sealing mechanism adapted tonormally fluidically seal said tube inlet and in use allow saidsurfactant delivery device to pass through said tube inlet, said sealingmechanism sealing around said surfactant delivery device, wherein a flowrate of gases through said jet outlet is controlled by the proximity ofsaid screw-on cap to said jet outlet, wherein the proximity of saidscrew-on cap to said jet outlet establishes a peak expiratory endpressure at said gases outlet of said pressure regulating device whilesaid external aperture is configured to be occluded and un-occluded by auser to vary a pressure at said gases outlet between a peak inspiratorypressure (PIP) with said external aperture occluded and a peak endexpiratory pressure (PEEP) with said external aperture un-occluded suchthat a portion of said gases flows through said external aperture tovent externally.
 19. A pressure regulating device as claimed in claim 18wherein said tube inlet and said gases outlet are substantially coaxial.20. A pressure regulating device as claimed in claim 18 wherein saidgases inlet is located substantially on an opposite side of said housingfrom said orifice branch.
 21. A pressure regulating device as claimed inclaim 18 wherein said orifice branch extends at an angle with respect tosaid gases outlet.
 22. A pressure regulating device as claimed in claim18 wherein said gases inlet extends at an angle with respect to said gasoutlet.
 23. A pressure regulating device as claimed in claim 18 whereinsaid housing comprises a flange at said gases outlet.
 24. A pressureregulating device for use with a breathing assistance apparatus thatconveys gases to an infant or a neonate requiring breathing assistance,the pressure regulating device comprising: a housing comprising: a gasesinlet adapted to in use be in fluid communication or integrated with thebreathing assistance apparatus; a gases outlet adapted to in use be influid communication with the infant or the neonate; a gas passagewaydefined between said gases inlet and said gases outlet, a valvepositioned between said gases inlet and an external aperture that isseparate and distinct from said gases inlet and said gases outlet, saidexternal aperture being fluidly connected to said gas passageway throughsaid valve, said external aperture providing a vent to atmosphere, saidvalve configured to establish a peak expiratory end pressure at saidgases outlet of said pressure regulating device, and said externalaperture being configured to be occluded and un-occluded by a user tovary a pressure at said gases outlet between a peak inspiratory pressure(PIP) with said external aperture occluded and a peak end expiratorypressure (PEEP) with said external aperture un-occluded such that aportion of said gases flows through said external aperture to ventexternally; and a tube inlet adapted to receive a surfactant deliverydevice therethrough to enable administration of surfactant to the infantor the neonate, wherein said tube inlet opposes said gases outlet, and asealing mechanism adapted to normally fluidically seal said tube inletand in use allow said surfactant delivery device to pass through saidtube inlet, said sealing mechanism sealing around said surfactantdelivery device.